Oil well completion apparatus



Feb. 21, 1939. MI ET AL 2,148,327

OIL WELL COMPLETION APPARATUS Filed Dec. 14, 1937 4 Sheets-Sheet lArman/M30 Eager Swat/u @ofizrt 75C Mazda/1 GHQ/pump Feb 21', 1939.

R SMITH ET AL 2,148,327

OIL WELL COMPLETION APPARATUS Filed Dec. 14, 1957 4 Sheets-Sheet 2Ill!!!" 0 23 ql l llll J6 gvwo'nm @qgz Smdflm fiobertfl Mazda/L Feb. 21,1939. R. SMITH ET AL OIL WELL COMPLETION APPARATUS Filed Dec. 14, 1937 4Sheets-Sheet 3 law.

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Q fi WM w m/ V aawaaiii QMJcm/Wio 1%gar Ema?! Feb. 21, 1939. 1 R. SMITHET AL OIL WELL COMPLETION APPARATUS Filed Dec. 14, 1937 4 Sheets-Sheet 4Patented Feb. 21, 1939 UNlTED STATES 2,148,327 OIL WELL COMPLETIONAPPARATUS Roger Smith and Robert A. Mueller, Houston, Tex, assignors toGray Tool Company, Houston, Ten, a corporation of Texas ApplicationDecember 14, 1937, Serial No. 179,780 16 Claims. (01. nae-15) Thepresent invention relates to oil well completion apparatus and methods.The principal object of the invention is to provide such apparatus andmethods which will permit the entire sequence of usual as well asunusual operations in completing a well while providing the maximumsafety against flow of fluid under high pressure from the well.

The apparatus and methods of the invention o utilize casing headformation equipment which gives the operator a wide choice in the safeperformance of operations which are necessary or desirable to beperformed, at any time prior to, during, or after the completion of thewell.

5 The apparatus utilized is such that it permits the use ofsubstantially all of the well-known pieces of control equipment of theprior art, such as master valves, blowout preventers, and the like, whenneeded, and the relegation of 59 these pieces of equipment to theposition of accessories when their function is no longer desired.

A particular object of the invention is to provide a method andapparatus which will permit the washing of the well through the tubing,and

g; the subsequent elevating of the tubing to flowing position andhanging and sealing the same by means of its hanger, without thenecessity of at any time breaking the tubing between the washing andhanging operations, so that the no connection from the lower end of thetubing in the well to the mud pump adjacent the well is never brokenuntil the well'is entirely sealed at completion.

In the recent development of apparatus of '5 this character, the trendhas been to provide equipment which will insure the maintaining of aseal both within the tubing and between the tubing and the casing at alltimes during the completion operations, particularly during thedangerous transition period when the gap is bridged between the washingand the hanging and sealing operations.

Most recently, progress has been made in the art in maintaining sealsboth with n the tubing 45 and between the tubing and the casing withequipment arranged in such fashion, and on such a foundation, that theindividual pieces of equipment used to maintain the seals at the variousstages of completion can be relegated go to the position of accessorieswhen no longer needed, rather than being tied up as a permanent part ofthe well structure after. the individual pieces of equipment haveperformed their functions.

5 While developments of this type are useful,

and have contributed greatly to the safety and efficiency of oil wellcompletion operations, it is nevertheless true that the primary safetyprecaution in well completion is to have available at all times meanswhich will permit the instantaneous discharge of mud into the bottom ofthe well to control the pressures therein. That is, most operators havelong sought for equipment which could be employed in a sequence ofcompletion operations permitting the connection between the mud pump andthe bottom of the tubing to be maintained at all times, par--' ticularlyduring the transition period between washing the well and hanging thetubing, and it is Weil -known in the oil fields that the confidence ofthe crew would be increased, and their work thus made more effective, ifequipment capable of maintaining this connection were provided.

The apparatus and methods disclosed herein not only provide for theperformance of all of the usual operations desirable or necessary duringcompletion, but also for the performance of unusual operations which maybe necessary to meet a particular situation, as well as providing afoundation which will adapt itself to future operations which may haveto be developed as deeper and higher pressure wells are drilled.

It will be understood that while the, particular application of thisinvention is to the completion of high pressure wells which are filledwith mud fluid, the invention is also adapted for use with facility forwells which are drilled and completed under pressure:

Another important object of the invention is to provide apparatus which.will increase the speed with which the well may be finally closed up byhanging and sealing the tubing in the casing head after the washingoperation is commenced, and particularly after the washing operation iscompleted and the equipment is being changed from its condition forwashing, to its condition for flowing the well. It will be understoodthat speedis of the essence at this critical time when the well has beenwashed and is coming in and before the tubing is hung and sealed.

In the drawings, which are illustrative of a preferred form of theinvention, but which may be modified to suit particular situations:

Figure l is a side elevational view partly in section of the equipmentat the surface of a high pressure well during the drilling stage;

Figure 2 is a view similar to Figure 1, showing the equipment at thestage when the tubing is being lowered into the well; I l

Figure 3 is a similar view, showing the equipment in condition when thetubing has been lowered into the well for the performance of the washingoperation, or for the setting of packers or the like;

Figure 4 is a similar view showing the equipment after the tubing hasbeen raised from the well after the performance of the above operations,preparatory to hanging the same;

Figure 5 is an enlarged vertical sectional view of the casing head,after the tubing has been 3;

Figure 6 is a side elevational view partly in section of the equipmentat the surface of the well, after the Christmas tree has been positionedon the casing head and showing the manner of removing the back pressurevalve from the tubing;

Figure 7 is a view similar to Figure 6 showing the completed well afterthe tubing back pressure valve has been removed;

Figure 8 is an enlarged vertical sectional view through the hanger andhanger collar, showing the construction of the back pressure valvecarried by the latter, and

Figure 9 is a view similar to Figure 8, showing the back pressure valveequipped with a strainer.

In Figure 1, the outside or upper string of cylindrical casing is shownat In, said string having attached to its upper end a casing head I 2provided with the well-known side outlets which may be closed by a bullplug ll or provided with a flow line controlled by a valve l3 as iswell-known in the art. Referring to Figure 5, the casing head i2 isprovided with an inside downwardly and inwardly tapered seat i8 aboveits side outlets, said seat being adapted to receive and seal with thelower tapered portion l3 of a hanger 20, the hanger being secured to theupper end of an inner string of casing 22. Mounted upon the casing headl2 and secured thereto by flange and bolt connections of like size, isan upper casing head 23 called a tubing head. The tubing head has atapered bore at its lower end adapted to closely embrace the taperedupper portion 24 of the hanger 20, and an upper tapered inside seat 25which receives and seals with the tubing hanger hereinafter described.Both the upper and lower faces of the hanger 20 are equipped withpacking rings. The above-described arrangement for supporting andforming a seal with the casing hanger 20 is disclosed in Patent No.2,082,413, Mueller et al., June 1, 1937.

The tubing head 23 is also provided with appropriate side outlets 26below its seating surface 25, any of which may be either closed by abull plug 30 or controlled by a flow valve 32 positioned in a flow linefrom said outlets.

Mounted upon the tubing head as a foundation, and connected thereto byflange and bolt connections of like size, is a master drilling valve 33,said valve being provided with a lower flange 33 of the same size as theupper flange of the tubing head 23 (Fig. 5), said flanges being securedtogether by bolts as shown and provided therebetween with an annularpacking II to insure a sealing connection.

Surmounting the master drilling valve are a pair of blowout preventers44 and 46, connected with each other and to the master drilling valvewith flange and bolt connections of like size.

Any kind of blowout preventer may be used, but the type employingsemi-cylindrical shoes 43 either manually or steam operated which engagethe inner pipe to form a seal therewith is preferred. It will beunderstood that the shoes used amass? in this type of preventer areinterchangeable, in order to seal with either a drill pipe, or a flowtubing.

The internal bores of the casing hanger 20, the tubing head 23, themaster drilling valve 33, and the blowout preventers 4| and 43 are atleast as large as, and preferably slightly larger than, the internaldiameter of the casing 22, in order to permit the insertion through thiscontrol equipment of a drill bit having a diameter substantially aslarge as the internal diameter of the upper string of casing 22. Thesecontrol devices must be of full bore as described above not only to passthe drill, but also to permit the passage into the well of the screenliner or packer and other devices which must be inserted therein bothprior and subsequent to the completion of the well.

In Figure 1, the drill stem is shown at having a bit '2 at its lowerend. It will be understood that the drill string is hollow, and that thebit is provided with suitable outlet openings so that the heavycolloidal mud used during drilling may be forced down through the drillstring and out through the openings in the bit to carry the cut tingsfrom the well upwardly through the casing and through the appropriateside outlets in the casing head, and also to keep the well filled withmud so that the head thereof will resist any tendency of the well toblow out during drilling and subsequent operations. The upper end of thedrill string connects with a swivel 54, which is of well-knownconstruction and need not be described. In general, the swivel includesmeans 33 for engaging the hook on the traveling block and a connectionwith the drill pipe which will permit the latter to be rotated withrespect to the swivel, as is well-known in the art. A hose 58 connectswith the upper portion of the swivel, the other end of said hose beingconnected with the upper end of a pipe in the side of the derrick, sothat mud or water may be supplied to the drill pipe through the swivelby pumping means P located adjacent the surface of the well, usually atthe side of the derrick.

If it is necessary at any time to insert the drill pipe into the wellwhen dangerous pressure ex ists therein, the same may be lowered pastthe blowout preventers with the master drilling valve 33 closed, afterwhich the blowout preventers are engaged with the drill pipe to form aseal. The master drilling valve may then be opened, and the drill pipelowered into the well, while the blowout preventers maintain a sealtherewith, the blowout preventers being operated alternately to pass thecollars of the drill string as is well-known. The blowout preventers maybe maintained in sealing engagement with the drill pipe during drillingif necessary.

When the well is full of mud, as will usually be the case when theapparatus of the present invention is employed, it may be unnecessary touse the blowout preventers to form a seal between the casing and thetubing during the insertion of the drill string and during the drillingoperation. However, the blowout preventers should be available duringthe drilling operation in case dangerous pressures are encountered, atwhich time they may be instantly closed around the drill string and thedrilling continued with the blowout preventers forming a seal betweenthe casing and the tubing.

The drill string should contain adjacent the lower end thereof as at 60,a back pressure valve of well-known type which will permit thedownauaaav ward flow of the drilling fluid through the drill string, yetwhich will prevent any upward flow 1 of fluid therethrough' from thewell. It is unnecessary to disclose the precise type of such backpressure valve, as the same are well-known in the art and may beillustrated by those shown in the patent Nos. 1,740,770, December 24,1929, and 1,872,139, August 16, 1932 to Gray et al.

"When the drilling has been completed, the drill string is removed withthe blowout preventers in open condition if the well is full of mud andin safe condition, or if dangerous pressures exist in the well, themaster drilling valve and blowout preventers may be used in the reversemanner from .that described above in the removal of the drill string.

Many operations may have to be performed at this dangerous stage ofcompletion, particularly operations to determine if the well is drilledto the proper depth for running the flow tubing. Such operations usuallyinvolve the removal of the drill string, application thereto of othertools, and relnsertion of the same into the well. It may be necessary atthis time to remove and reinsert the drill string many times. Theoperations referred to may include: running formation logging devices,drilling the rat hole, running the drill stem testing tube, reaming outthe rat hole, and setting a perforated liner or strainer and packer. Thebore through the master drilling valve 36, blowout preventers M and 46,and tubing head 23 is large enough to permit passage of all devicesnecessary to perform the above operations, and such as the screen lineror packer, and the control equipment disclosed may be v manipulated toaccomplish the perhaps usual operations above, as well as unusualoperation without losing control of the well.

When operations of the above type have been completed, the time willhave arrived when it is desired to lower the flow tubing into the well.Before the well is ready to flow through this tubing, it may benecessary to utilize the same in performing otheroperations involvingmanipulating the tubing, such as setting a packer and so forth.

If the well is mudded up and there is no danger of high pressure fluidbeingreleased from the well, the tubing may be built up in sections, one

attached to another by means of the conventional collars as the tubingis lowered into the well. The tubing may be open at its lower end, andthe blowout preventers need not be used other than to support the tubingwhile sections thereof are being assembled to that portion of the tubingalready in the well.

From the measurements pre iously taken, it will be known what portion ofthe tubing is to be positioned at the point of hanging, and at thispoint a special hanger collar 62 is built into the tubing string insteadof a conventional collar.

Referring to Figure 8, this collar comprises a sleeve interiorlythreaded at its lower end at 64 for engagementwith the upper end of thetubing section 66, and also interiorly threaded at its upper end as at68 for the reception of the lower end of the lowering tubing section 10.This special collar is also exteriorly threaded at its upper end at 12,whereby the tubing hanger 14, which has a lower cylindrical interiorlythreaded sleeve 16, may be screwed to the upper end of said collar.

While it is preferred ,to employ a threaded connection between thehanger l4 and the special collar 62, any other appropriate connectionwhich can be quickly yet rigidly and permanently effected will suffice.

The hanger ll has a central bore 18 therethrough, which with theinterior of its screw threaded portion 16, is of sufficient diameter tofreely move along the tubing section between the special collar 62 andthe next adjacent collar of the tubing above said special collar.

When the special collar I2 is built into the tub ing string, the hangeris positioned above the same and around the upper tubing string 10,being left unconnected with the collar 62 as shown in Figure 2.

Before the tubing is built up during its insertion, any desired type ofdevice is secured to the. lower end thereof, such as a packer or thelike,

and in operating such devices at the bottom of the well, it will usuallybe necessary to lower the tubing into the well until the special collar2 is below the control equipment and the casing head and an appreciabledistance down in the well as shown in Figure 3. For instance, to set'apacker in order to isolate particular sands, it may be necessary toforce the tubing downwardly a considerable distance and with greatpressure in order to set the packer. It would be possible, of

course, to closely anticipate the amount of downward movement necessaryto completely expand the packer, and build into the tubing aconventional hanger at such point that it would just seat in the bowl ofthe tubing head 23 at the completion of the downward movement of thetubing to expand the packer, after which the well could be flowedthrough the tubing.

However, such a method is subiect to the disadvantage-that when extremepressure is put on the tubing to expand the packer, the former, beingperhaps thousands of feetlong'will become bent in many places throughoutits length, and it is desirable to remove these bends-before the tubingis finally hung. The oil and gas flows from the well through the tubingunder considerable pressure, and this pressure flow causes vibrationswhich eventually result in leakage if the tubing connections are nottight, and it is evident that if the tubing is distorted, ultimateleakage of the same is inevitable. Some wells now being completed mayflow under their own pressure for many years, so that the permanency ofthe tubing installation is quite important.

When the tubing is lowered for any operations such as the setting of apacker, the special collar 62 is positioned in the tubing string at thedesired point of hanging, and the hanger 14 is only loosely mounted onthe tubing 10 above said collar. The tubing is lowered into the well toset the packer,

or perform any other similar operation, but the hanger "is kept inposition above the casing head and above the control equipment if thelatter is used, so that the tubing may be forced down into the well asfar as necessary to perform the desired operation, with the specialcollar 62 disposed at the point of hanging going on down into the wellbelow the casing head as far as necessary as shown in Figure 3. Aremovable strap 19 of any appropriate type may be bolted around thetubing beneath the hanger ll to hold it in place above the controlequipment. The tubing may be moved downwardly until the hangerpasseswhich time the hanger I4 is quickly and rigidly threaded onto thetubing at the collar 02, and lowered to seating position in the tubinghead 28 as shown in Figure 5.

Because of the apparatus and method which permits subsequent elevationof the tubing after the packer setting operation, all of the bends inthe tubing resulting from the packer. setting or other operations may beremoved before the tubing is finally hung for the flowing of the well.

While in most cases, the bore through the hanger 14 need only besufilcient so that it can move from the special collar 82 to the nextcollar in the tubing string above the same, if desirable, the said boremay be large enough to pass over the collars in the tubing string abovethe special collar, in which case theithreaded portion 12 of the specialcollar 82 may be of increased diameter to fit the lower threaded portionof the hanger, said collar being yet of small enough diameter to passfreely down into the casing. However, if any operation is expected whichwill necessitate an unusually great movement of the tubing down into thewell after the special collar r is built into the tubing, and it isdesired to take up this movement before hanging the tubing, the stringof tubing I0 above the hanger may be made of sufficient length to takecare of this movement without using a hanger having a larger bore.

Referring to Figure 3, the upper end of the tubing may at all times beconnected with the swivel, and the rubber hose 58 extending to the pumpsmay be at all times in communication with the lower end of the tubingduring the above operations, and at no time during insertion of thetubing with or without appliances secured to the bottom thereof, duringthe setting or operation of these appliances, and during the elevationand hanging of the tubing, will it be necessary to break the tubing.Therefore, mud may be pumped into the bottom of the well through thetubing immediately in case a dangerous condition is encountered. Inequipment of the prior art, the hangers used, while perhaps capable ofbeing lowered through the control equipment, cannot be built into thetubing without breaking the latter, thus leaving the well without thesafe guard of being able to instantly pump mud to the bottom of the sameduring the time the hanger is being built in.

If the well is full of mud and in safe condition,

the blowout preventers need not be used, but if a dangerous pressurecondition in the well is apparent, they may be used during insertion ofthe tubing, during setting or operating of any appliances at the bottomof the tubing, and during the raising of the tubing to the position ofFigure 4, and while rigidly securing the hanger thereto and thesubsequently seating the hanger.

With the well full of mud, it is necessary to wash the same and replacethe column of mud in the casing with a column of other lighter liquid sothat the well will flow. It may be desirable to provide a flow of wateror other liquid upwardly outside the screen or strainer at the bottom ofthe casing, if such devices are used, in order to clear the perforationsthereof so that the oil can pass into the casing. This washing of thewell is an operation at the bottom thereof similar to the other perhapsnecessary operations described above.

Referring to Figure 8, the special collar 82 is provided on its interiorwith a central series of reversely arranged threads 80 into which isthreaded a valve housing 92 having a valve seat amass? 84 secured withinthe lower end thereof. A valve cage 98 has a threaded extension 88 whichis threaded onto the lower end of said housing, holding the valve seatin place. Arranged within the valve cage is a ball valve member Inormally forced against its seat by a valve spring iOi carried withinthe cage ll. The tension of the spring llll is sufficient to keep thevalve normally closed, but is such that the valve may be moved from itsseat under the pump pressure to permit a downward flow of washing wateror mud into the well through the tubing.

With the well full of mud, the tubing is lowered into the well aspreviously described with the back pressure valve therein until thespecial collar is an appreciable distance down in the well and below thecasing head, and with the hanger ll held above the control equipment, ifpossible, or at least, above the tubing head. When the tubing has beenlowered, to washing position. the blowout preventers are engagedtherewith and clear water or otherfluid is pumped downwardly through thetubing past the back pressure valve and out through the lower end of thetubing to wash the well. The hose 58 is connected with a two way valveI02 located adjacent the well, (shown diagrammatically in Fig. 3), sothat either mud or water may be pumped into the well through the tubingfrom the lines M or W respectively. If the well is being washed withwater, a quick shift of the valve I02 when dangerous pressures areencountered will permit the relatively heavy mud to be instantaneouslypumped to the bottom of the well to quench the high pressure therein.Both outside and/0r inside washing may be performed as desired. Usuallythe lower end of the casing is provided with a strainer or screen, andit is conventional to equip the lower end of the tubing and the lowerend of the strainer or screen with cooperating means to enable theformer to seal with the latter, so that when the washing fluid is pumpeddownwardly through the tubing, it will pass out through the lower end ofthe screen, upwardly around the outside thereof, and up through thecasing to discharge through the appropriate side outlets inthe casinghead.

The lower end of the strainer or screen may also be equipped with a backpressure valve as is conventional, which may be opened mechanically bythe tubing or in response to the pressure of the fluid flowingdownwardly therethrough, which valve will close at thetermination of thewashing operation so that all of the oil will enter the casing throughthe perforations in the screen or strainer.

During inside washing of the well, the tubing is raised to a pointwithin or above the screen or strainer and fluid is forced downwardlythrough thetubing and into the casing through the lower end of thetubing, the fluid rising in the casing and discharging through theappropriate side outlets, in this instance through the side outlets 26in the tubing head 23.

During either inside or outside washing through the tubing, the blowoutpreventers are engaged therewith so that various movements of the tubingmay be effected as desired with safety; that is, the tubing may bemanipulated up or down or rotated, and the blowout preventers maintain aseal therewith at all times.

During the washing operations, and during movements of the tubingincident thereto, not only will the blowout preventers provide controlof the well between the casing and tubing, but

, 9,148,897 also the back pressure valve I00, while permitting downwardflow of the washing fluid, will prevent upward flow of high pressurefluid from the well.

At the termination of the washing operation, either outside or inside orboth, the tubing is elevated to'the position of Figuregi, with itsspecial collar 82 positioned above the control equipment, it beingevident that this collar may be safely moved through the controlequipment without losing control of the well by alternate operation .ofthe blowout preventers 44 and 48 as previously described. When thetubing has reached this position, the hanger I4 is quickly and rigidlysecured to the tubing by screwing the same onto the special collar 62 atthe threads I2, after which the tubing is then lowered to hangingposition as shown in Figure 5. During this lowering of the tubing withthe hanger in place, control of the well may be maintained by keepingthe lower blowout preventer 44 engaged with the tubing until the hangeris moved below the upper blowout preventer '46, after which the lattermay be engaged with the tubing section 10 above the hanger, followed bythe opening of the lower blowout preventer 44 and the lowering of thehanger to its seat.

Asshown in "Figure 5, the tubing head 23 is provided with looking screwsIIO extending laterally through the flange 40 thereof, said screws beingsurrounded by a suitable packing III, the

latter being held in place by glands I I2 threaded into openings inflange 40 surrounding the looking screws.

When the hanger is seated as shown in Figure 5, the locking screws IIOare moved inwardly until their ends engage the upper beveled sur-, faceH2 of the hanger, thus locking the hanger in its seat and compressingthe packing rings H4 which extend completely around the hanger intosealing engagement with the bowl of the hanger seat in the tubing head23.

At this time, the sealing engagement of the hanger with itsseat providesa permanent seal between the casing and the tubing, and the backpressure valve I provides a closure within the tubing against upwardflow of fluid therethrough from the well.

It will be apparent from the above-described operations that aconnection for instantaneous flow of mud from the pumps through thelower end of the tubing in the well is permanently maintained from thetime the washing of the well is commenced, until the time when thetubing hanger is permanently hung, sealed, and locked in the casinghead, withthe well completely closed.

If the tubing is to be lowered into the well under pressure, as.distinguished from a situation in whlchthe well is full of mud, thelower end of the tubing may be equipped with a frangible disc closure ofwell-known type, and the back pressure valve pensed with. In thissituation, the tubing is lowered through the control equipment while thesame maintains a seal therewith. As previously described, the hanger isrigidly attached to the tubing by the collar located at the point ofhanging of the tubing, and the tubing is hung, sealed, and looked asdescribed above, without opening up the well for flow of high pressurefluid either through the tubing or through the casing at any time.

If necessary, when inserting the tubing under pressure, any necessaryoperations at the bottom of the well may be effected prior to the in thetubing may be 'dis- I permanent hanging of the tubing, by attachingthese devices, such as packers, to the lower end of the tubing andlowering them by means of the tubing into the well, while controlismaintained by the control equipment as above-described. During suchlowering, the point of hanging of the tubing may be lowered into thewellto a point below the casing head 23, while the hanger, thoughmounted on the tubing, is retained above the casing head or the controlequipment. When operations are completed, the tubing is elevated untilits point of hanging is above the control equipment, the hanger quicklyand rigidly attached thereto, and is then lowered and locked in itsseat. By reason of the construction of the hanger and its manner ofapplication to the tubing, after any necessary operations are performedwith the tubing at the bot- I tom of the well, the' same may be elevatedand the hanger attached thereto and hung without any loss of time. It iswell understood that in oil well completion operations, the quicker thehanger can be attached, hung, and sealed, the better. I i

When the hanging and sealing operations have been completed, the upperstring of tubing I0 is unscrewed from engagement with the threads 68 ofthe collar 62 and removed from the casing head equipment. Furthermore,the master drilling valve 35 and the blowout prewenters and 46, havingnow performed their function, may be safely removed from the casing headequipment and relegated to the position of accessories. This controlequipment is quite heavy and expensive, and its removal to the positionof accessories permits its immediate use on other wells in the field, orit may be kept available at the same well if its function is againdesired.

After the removal of the control devices as described above, theChristmas tree equipment be of any appropriate type, and is shown com- Iprising a master manifold valve I mounted directly on the tubing head23, said valve being surmounted by a cross ,I 22 which may havepositioned above the same a further Christmas tree control valve I24,and also another control valve I26 secured to a side outlet from saidcross. The

other outlet from the cross opposite valve I26 may be similarly equippedwith a control valve, ormay be closed with a bull plug I28, as desired.

The Christmas tree may be assembled and stabbed onto the casing head asa unit.

The master manifold valve I20 is much smaller and offers a much lesspressure area to the fluid in the well than did the master drillingvalve 36 which formerly occupied its position on the tubing head.

The master manifold valve I20 is connected in sealing engagement withthe upper flange 40 of the tubing head by bolts, as shown, and theconnecting flanges are of like size. Furthermore, the cross I22 isconnected with the valvev I20, and with the auxiliary control valves I24and I26 with flange and bolt connections of like size. I I

After the Christmas tree is mounted on the casing head as describedabove, the well is ready to flow after the tubing is opened. If a backpressure valve 02 was used to close off the tubing, it is removed ashereinafter described. A stufilng box I40 is provided above the valveI24, being carried by a flanged adapter I42 bolted to the upper flangeof the valve I24. This stuffing box is built up around a solid rod I44provided at its lower end with a tool shown in the form of screw threadsI46 adapted to engage threads I 40 in the upper interior of the valveassembly 02, these threads being reversely arranged with respect to thethreads 80 between the valve housing 92 and the hanger 14. The solid rodI44 .is lowered down through the valves I24 and I20 and the threadedtool I46 is screwed into the threads I48 of the valve housing. and aftersaid tool is completely threaded into the valve housing, furtherrotation of rod I44 removes the valve housing and valve from the collar62, after which the tool may be elevated to lift the valve assembly toposition above the master manifold valve I20 as shown in the dottedlines in Figure 6, when said valve may be closed.

The well is under control during the removal of the valve assembly, asthe stufflng box I40 forms a seal around the solid rod I44. When thevalve assembly has been elevated above the valve I20 and the latter ,isclosed, the stufling box I40 and the solid rod carrying the valveassembly are removed, and the conduit extending from the upper end ofthe valve I24 may be closed by a bull plug or a pressure gage fitting asdesired, or a further flow line and choke as shown leading from valveI26 may be connected to the upper opening from the valve I24.

If the tubing has been closed by a frangible disc near its lower end, aspreviously described, it can be opened up when the well is ready to flowby opening the valve I24 while the valve I20 is closed, dropping aweight into the cross, closing the valve I24, opening the valves I20 andI26, thus permitting the weight to drop through ,the tubing, destroyingthe frangible disc to permit the well to flow through the Christmas treeside outlet controlled by the valve I26.

After opening up the tubing, the well is in condition for flowingthrough any of the outlets from the cross I22 as shown in Figure '7.

The present invention provides a marked flexibility of Cltl'Ol, and notonly gives the operator a wide choice of what operations can be safelyperformed, but also a wide choice of the manner in which theseoperations may be safely carried out. For instance, when the completionof the well has arrived at the stage of Figure 6, with the Christmas.tree mounted on the casing head and the back pressure valve still inplace within the collar 62, washing of the well may be performed throughthe Christmas tree. At this time, the solid rod I 44 and stuffing boxI40 would not be present in the apparatus. When in this condition, aconnection could be made to either of the valves I24 and I26 or througha valve positioned in place of the bull plug I20, and washing fluid ispumped downwardly through the tubing past the back pressure valve, andout through the bottom of the tubing, passing upwardly through thecasing and discharging from the side outlets in the tubing head 23. Thatis, the well might be washed with the Christmas tree in place, ratherthan washing the well with the control equipment of Figure 3 in place.

Some operators may prefer to only perform the outside washing of thewell with the control equipment mounted as shown at Figure 3, leavinginside washing of the well until the rod similar to the rod I44.

Christmas tree is in position and the well completely buttoned up. Theflexibility of operation described above is obviously of pronouncedadvantage.

After the well has been completed as above described, it may benecessary to perform other operations subsequent to completion, perhapsafter the well has flowed for a considerable time. With the well stillunder high pressure, the tubing may be plugged at any point by anywellknown type of tubing spear, said spear being set by a tool carriedon the lower end of a solid The spear is inserted without opening thewell to flow of high pressure fluid by reversing the operationsdescribed in connection with the removal of the valve housing and valveillustrated in Figure 6.

With the tubing closed, the Christmas tree is removed and replaced withthe control equipment of Figure 4, after which the upper string oftubing 10 is lowered and engaged with the hanger, the blowout preventersengaged with the lowering tubing 10, after which the locking screws IIOare retracted to permit elevation of the tubing and hanger, controlbeing maintained by the blowout preventers. The tubing may be com-,pletely removed, if the spear plug is disposed at the lower end of thetubing, to permit the attachment to the lower end thereof of suchdevices as a packer, for instance, to isolate particular sands.

The tubing may be lengthened or shortened, to obtain a better oil-gasratio, while control is maintained both through the tubing and casing byfollowing the sequence of operations described above in manipulating thecontrol equipment. Such lengthening or shortening of the tubing willinvolve raising the hanger 14 through the control equipment, looseningit from its collar, and then again rigidly securing it to a new collarbuilt into the tubing at the proper point of hanging after the changesare effected. The hanger is then lowered to its seat and locked, theChristmas tree returned to position on the tubing head 23, and the spearplug removed as will be obvious from the preceding description.

In Figure 9 the back pressure valve housing 62' has formed integraltherewith an upwardly extending strainer S, the latter being acylindrical sleeve with a plurality of openings therein. It will benoted that this strainer is centrally disposed with respect to thehousing, so that the lowering tubing 10 may pass down over the same whensaid tubing is secured to the collar 62. Instead of the threads I 46 onthe interior of the valve housing in the embodiment disclosed in Figure8, the upper end of the strainer carries an interiorly threaded socketI46 which is adapted to receive the threads on the lower end of theremoving rod I44.

The strainer serves to protect the back pressure valve from any materialpassing downwardly through the tubing which might foul said valve. Thethreads I48 are reversely arranged with respect to the threads 00'between the valve housing and the collar 62, so that when the removingrod is threaded into the upper end of x the strainer in the same manneras previously described, the back pressure valve will be removed fromthe collar 62. The back pressure valve and strainer may be removed withsafety in the same manner as described in connection with Figure 6.

Important features of the present invention are the ability to maintaincirculation through the tubing during-the performance of operations atthe bottom of the well, such as the setting of packers, and duringsubsequent elevation and hanging of the tubing, as well as the abilityto maintain circulation from the pumps to the bottom of the tubingduring the washing of the well, and subsequent elevation and hanging ofthe tubing. The above operations may be performed without breaking thetubing between the swivel and the bottom of the hole at any time,whereby circulation may be maintained during the entire proceduresinvolved.

Notwithstanding that devices are available for the handling of wellsunder pressure without the help of heavier fluid, such as mud, and eventhough in most instances the procedure is planned to avoid the use ofmud, it is generally accepted in practical oil well completion thatwhenever a question arises concerning the ability of the controlmechanism to hold the pressure in the well, the use 01' ahead of mudshould be resorted to as quickly as possible. With the tubing unbrokenbetween the swivel and the bottom of the well at all times during thedangerous operations, the injection of mud to the bottom of the well canbe performed by merely switching a valve at the pump manifold, therebychanging the fluid being inserted from oil or water as the case may beto water or mud in proportion to the weight desired. The ability toquickly inject mud into the hole remains the most effective safetyfeature in guarding wells against blowouts.

It will be apparent that this inventionmay be used in performing throughthe sequence of control operations in association with a wide choice ofdrilling methods, such as cable tool and rotary methods under pressure,rotary systems using both mud and pressure control operations. Theinvention herein described aifords a choice of settings at the bottom ofthe well, including completions with a liner, screen, and packer, andwith perforated liner and the setting of production packers eitherduring or after completion.

The invention of this application is an improvement in the method andapparatus for completing wells described and claimed in the applicationof Roger Smith, Serial No. 736,635, filed July 24, 1934, and applicationSerial No. 58,821, Robert A. Mueller and Roger Smith, filed January 13,1936.

It will be obvious that various changes may be made in the method andapparatus described herein without departing from the invention.

We claim:

' 1. In well completion equipment, a tubing comprising upper and lowersections, a tubing collar for connecting saidsections, said collarhaving a bore threaded interiorly at its lower end for securing saidlower section of tubing, and interiorly at its upper end for securingwith said upper section of tubing, a removable valve housing securedwithin said collar between the upper and lower threads thereof, a tubinghanger having aibore surrounding the upper section of tubing and mountedfor longitudinal movement thereon above said collar, said hanger borehaving threads therein, and cooperating exterior threads on the upperend of said collar, whereby said hanger may be rigidly secured to saidcollar, and said upper section of tubing detached therefrom afterhanging said lower section of tubing in the well with said hanger, saidvalve housing having means for receiving a-tool to remove the same fromsaid collar after the lower section of tubing is hung.

2. In well completion equipment, a tubing collar for connecting uppertubing, said collar being of size and shape adapting it for loweringthrough the casing head and easing of a well, saidcollarhavingmeansarranged torrigidconnectionwith a lower section oftubing, and meanswhereby it may be detachably connected with an upper section of tubing,a unitary valve housing detachably secured within said collar, saidhousing having a valve therein providing for passage offluid downwardlytherethrough but providing against passage of fluid upwardlytherethrough, and means on said collar arranged for rigid connectionwith a tubing and lower sections of.

hanger preparatory to hanging said lower section of tubing in the wellwith said hanger, said valve housing having means for receiving a toolto remove the same as a unit from said collar after the lower section oftubing is hung.

3. In well completion equipment, a tubing col- 1 lar for connectingupper and lower sections of tubing, said collar being of size and shapeadapting it for lowering through the casing head and casing of a well,said collar having means at its lower end arranged for rigid connectionwith a lower section of tubing, and means at its upper "end whereby itmay be detachably connected with an upper section of tubing, a unitaryvalve housing detachably secured within said collar between said means,said housing having a valve therein providing for passage of fluiddownwardly therethrough but providing against passage of fluid upwardlytherethrough, and means on the upper end of said collar arranged forrigid connection with a tubing hanger preparatory to hanging said lowersection of tubing in the well with said hanger and removing said uppersection of tubing, said valve housing having means for receiving a toolto remove the same as a unit from said collar after the lower section oftubing is hung and the upper section of tubing is removed from saidcollar.

4. In well completion equipment, a tubing collar for connecting upperand lower sections of tubing, said collar being of size and shapeadapting it for lowering through the casing head and casing of a well,said collar having means at its lower end arranged for rigid connectionwith a lower section of tubing, and means on the interior of its upperend whereby it may be detachably connected with an upper section oftubing, a unitary valve housing detachably secured within said collarbetween the upper and lower ends thereof, said housing having a valvetherein providing for passage of fluid downwardly therethrough butproviding against passage of fluid upwardly therethrough, and a hangerrigidly secured to the exterior of said collar at the upper end thereoffor hanging the lower section of tubing in the well, said valve housinghaving means for receiving a tool t9 remove the same as a unit from saidcollar after the lower section of tubing is hung, and packing means onthe exterior of said hanger for forming a seal with the interior of thecasing head of the well.

5.A tubing collar for use in completing an oil well, said collarbeing ofsize and shape adapting it for lowering through the casing head andcasing of a well, said collar having a bore therethrough and havingmeans at its upper end arranged for rigid connection with a tubinghanger, and means at its lower and arranged for rigid connection with alower section of tubing, said collar having means on its interior fordetachably connecting an upper section of tubing therewith, and meansbelow said last-named means for detachably securing a back pressurevalve in said collar, the bore oi said collar above said lastnamed meansbeing large enough to permit removal of the back pressure valve as aunit there-* from when the tubing is hung and the upper section oftubing is detached from said'collar.

6. A tubing collar for use in completing an oil well, said collar havinga bore therethrough and being of size and shape adapting it for loweringthrough the casing head and casing of a well, said collar having meansonits exterior arranged for rigid connection with a tubing hanger andmeans at its lower end arranged for rigid connection with a lowersection of tubing, said collar having means at its upper end fordetachably connecting an upper section oi tubing therewith, and means insaid bore for detachably securing a back pressure valve therein, thebore of said collar above said last-named means being large enough topermit removal of the back pressure valve as a unit therefrom when thetubing is hung and the upper section of tubing is detached from saidcollar.

7. In well completion equipment, a tubing collar for connecting upperand lower sections of tubing, said collar being of size and shapeadapting it for lowering through the casing head and casing of a well,said collar having means arranged ior rigid connection with a lowersection oi tubing, and means whereby it may be detachably connected withan upper section of tubing, a unitary valve housing detachably' securedwithin said collar, said housing having a valve therein providing forpassage of fluid downwardly therethrough but providing against passageof fluid upwardly therethrough, and having a strainer positioned abovesaid valve to protect the sameI and means on said collar arranged forrigid connection with a tubing hanger preparatory to hanging said lowersection of tubing in the well with said hanger, said valve housinghaving means for receiving a tool to remove the same as a unit from saidcollar after the lower section of tubing is hung.

8. In completion apparatus for use on an oil well which is producedthrough flow tubing lowered into a casing, a casing head having aninside supporting seat, a tubing hanger supported in said seat, a tubingcollar rigidly secured to said hanger, said collar being or size andshape adapting it for lowering through said casing head and the casingof the well, said collar being rigidly connected with the upper end ofthe tubing to suspend the same from said hanger and having a boretherethrough, and a unitary valve housing detachably secured within saidbore, said housing having a valve therein providing for passage of fluiddownwardly therethrough but providing against passage of fluid upwardlytherethrough, said valvehousing having means for receiving a tool toremove the 'same as a unit from said collar after the tubing issuspended in the well from said hanger.

9. In completion apparatus for use on an oil well which is producedthrough flow tubing lowered into a casing, a casing head having aninside supporting seat, a tubing hanger supported in said seat, a tubingcollar rigidly secured to said hanger and extending below the same downinto said casing head, said collar being of size and shape adapting itfor lowering through the casing head and casing of the well, said collarbeing rigidly connected with the upper end of the tubing to suspend thesame from said hanger and having a bore therethrough, and a backpressure valve removably secured within said bore, said valve providingfor passage 01' fluid downwardly therethrough but providing againstpassage of fluid upwardly therethrough.

10. In completion apparatus for use on an oil well which is producedthrough flow tubing lowered into a casing, a casing head having aninside supporting seat, a tubing hanger supported in said seat,vpackingmeans between the outer wall 01' said hanger and the wall of said seatto form a seal for closing oil. the upper end of the casing, a tubingcollar rigidly secured to said hanger and extending below the same downinto said casing head, said collar being of size and shape adapting itfor lowering through the casing head and casing 01' a well, said collarbeing rigidly connected with the upper end of a lower Section of tubingto suspend the same from said hanger, and having means whereby it may bedetachably connected with an upper section of tubing, said collar havinga bore therethrough, and a back pressure valve removably secured withinsaid bore, said valve providing for passage of fluid downwardlytherethrough but providing against passage of fluid upwardlytherethrough.

11. In completion apparatus for use on an oil well which is producedthrough flow tubing lowered into a casing, a casing head having aninside supporting seat, a tubing hanger supported in said seat, a tubingcollar rigidly secured to said hanger and extending below the same downinto said casing head, said collar being of size and shape adapting itfor lowering through the casing head and casing of a well, said collarbeing rigidly connected with the upper end of a lower section of tubingto suspend the same from said hanger. and having means whereby it may bedetachably connected with an upper section of tub: ing, said collarhaving a bore therethrough and a back pressure valve with a strainerabove the same removably secured within said bore, said valve providingfor passage of fluid downwardly therethrough but providing againstpassage of fluid upwardly therethrough, said strainer serving to protectsaid valve.

12. In well completion equipment, a casing, a casing head having ahanger seat, a tubing in said casing, said tubing being made up ofsections of pipe attached together by collars, one of said collars beinglocated at the point of hanging of said tubing, and being rigidlyconnected with the upper end of a lower section 01' tubing anddetachably connected with the lower end of an upper section of tubing,whereby it divides said tubing into a lower flow section and an upperremovable section, means in said one of said collars for preventingupward flow oi fluid through said tubing from the well while providingfor downward flow oi fluid therethrough, a hanger mounted forlongitudinal movement on said upper removable section of tubing, meanson said hanger arranged for rigid connection with said one of saidcollars to thereby rigidly secure said hanger to said lower flow sectionof tubing, whereby said hanger may be lowered into said seat to suspendsaid lower flow section of tubing in said casing, and said upper sectionof tubing detached from said one of said collars and removed from theequipment.

13. In .well completion equipment, a casing, a casing head having ahanger seat, a tubing in said casing, said tubing being made up ofsections of pipe attached together by collars, one of said collars beinglocated at the point of hanging of said tubing, and being rigidlyconnected with the upper end or a lower section oi tubing and detachofhanging of the latter ably connected with the lower end oi! an uppersection of tubing, whereby it divides said tubing into a lower flowsection and an upper removable section, a unitary valve housingdetachably connected within said one of said collars, said housinghaving a valve therein providing for passage of fluid downwardlytherethrough but providing against passage of fluid upwardlytherethrough, said valve housing having means for receiving a tool toremove the same as a unit from said one of said collars, a hangermounted for longitudinal movement on said upper removable section oftubing, means on said hanger arranged for rigid connection with said oneof said collars to thereby rigidly secure said hanger to said lower flowsectionof tubing, whereby said hanger may be lowered into said seat tosuspend said lower flow section of tubing in said casing, and said uppersection of tubing and valve housing may be removed from said one of'saidcollars to flow the well.

14. In well completion apparatus, a casing, a tubing in said casing, acasing head having a hanger seat, a tubing hanger mounted foriongitudinal movement on said-tubing above the point of hanging of thelatter for disposition above said casing head when said tubing islowered into said casing with its point of hanging below said casinghead, a collar for securing the sections of tubing together disposed atthe point of hanging of said tubing, and being rigidly connected withthe upper end or a lower section of tubing and detachably'connected withthe lower end of an upper section of tubing, said collar dividing saidtubing into a lower flow section and an upper removable section, meanscarried within said collar for preventing upward flow of fluid throughsaid tubing from the well while providing for downward flow oi fluidtherethrough, and means on said hanger arranged for rigid connectionwith said collarto thereby rigidly secure said hanger to said lower flowsection of tubing, whereby said hanger may be lowered into said seat tosuspend said lower flow section of tubing in said casing, and said uppersection of tubing may be detached from said collar and removed from theequipment.

15. In well completion apparatus, a casing, a tubing in said casing, acasing head having a hanger seat, a tubing hanger mounted forlongitudinal movement on said tubing above the point for dispositionabove said casing head when said tubing is lowered into said casing withits point of hanging below said casing head, a collar for securing thesections oi! said tubing together disposed at the point of hanging ofsaid tubing, and being rigidly connected with the upper end of a lowersection of tubing and detachably connected with the lower end of anupper section of tubing, said collar dividing said tubing into a lowerflow section and an upper removable section, a unitary valve housingdetachably secured within said collar, said housing having a valvetherein providing for passage of fluid downwardly therethroughbutproviding against passage of fluid upwardly therethrough, said valvehousing having means for receiving a tool to remove the same as a unitfrom said collar, and means on said collar arranged for rigid connectionwith said hanger to'thereby rigidly secure said hanger to said lowerflow section of tubing, whereby said rigidly secured hanger may belowered into said seat to suspend said lower flow section of tubing insaid casing, and said upper section of tubing and valve housing may beremoved from said collar to flow the well.

16. In well completion equipment, a casing, a casing head having ahanger-seat, a tubing in said casing, a collar disposed at the point ofhanging of said tubing connected rigidly with the tubing below anddetachably with the tubing above, said collar dividing said tubing intoa lower'flow section and an upper removable section, control equipmentfor forming a seal between said casing and said tubing mounted abovesaid casing head, said tubing extending through said control equipmentwith said collar disposed below said casing head while performingoperations with said tubing at the bottom of the well, a hanger mountedfor longitudinal movement'on said upper section of said tubing, saidhanger being of size and shape adapting it for lowering through saidcontrol equipment and being disposed above said casing head during theperformance oi. said operations, whereby said control equipment may beactuated to form a seal with said tubing when desired with said hangereither above or below said control equipment, a removable back pressurevalve in said collar, means on said hanger arranged for rigid connectionwith said collar to thereby rigidly secure said hanger to said lowerflow section of tubing, whereby said tubing maybe elevated after theperformance of said operations to position said collar above saidcontrol equipment, said hanger rigidly secured to said lower flowsection of tubing and thereafter lowered to said seat to suspend saidlower flow section of tubing in said casing without at any time openingthe well for new through said tubing or between said tubing and saidcasing.

\ ROBERT A. MUmLER.

ROGER SMITH.

